100 ' REPORT OF THE 



formation is known, until reaching Tuscola county. On the 

 S. E. I sec. 16, T. 12 N., 9 E., are found numerous fragments of 

 a compact, blue, non-fossiliferous limestone, which has been 

 quite extensively employed for burning-. Rock is also felt in 

 the bed of Cass River, at this place.* 



On' the S. W. J sec. 22, T. 16 N., 9 E. (Sebewaing), Tuscola 

 county, are found abundant fragments of the lower arenaceous 

 member of the Carboniferous limestone, containing an Allo- 

 risma. Further north, on the N. W. J sec. 13, T. 16 N., 9 E., 

 half a mile above the mouth of Cheboyong Creek, is a distinct 

 outcrop of an arenaceous, yellowish limestone, containing nu- 

 merous specimens of Allorisma clavata, and other species iden- 

 tical with the one found at Grand Rapids and Bellevue. In 

 this sandstone occurs a thin layer, highly calcareous and ex- 

 ceedingly tough. The next outcrop occurs at the northern 

 extremity of Stone Island (Shung-woi gue), in Saginaw Bay. 

 The rock rises but four or five feet above the water, and is 

 generally much brecciated. It is for the most part calcareous, 

 but exhibits bands and patches of an arenaceous character; 

 and the beach is strewn with fragments apparently thrown up 

 from a greater depth, which seem to belong to the arenaceous 

 strata exposed at Cheboyong Creek. Allorisma occurs here, 

 and geodes are not unfrequent. The lower arenaceous layers 

 appear again on North Island (Ash-qua-guin dai-gue). 



On the south side of Wild Fowl Bay, is a characteristic out- 

 crop of the formation, extending along nearly the whole shore. 

 The dip is very slight toward the south-east. The greatest 

 actual exposure is only four feet, but the rock undoubtedly 

 rises in the bank to the height of 15 feet above the water. The 

 following stratigraphical characters were noted: 



F. Limestone, argillaceous, cherty, perforated extensively 



by a Syringopora, 1 in. 



E. Limestone, compact, bluish, weathering white, 1 ft. 



*At»out the forks of the Cass, above and below, are found numerous fragments of a lime- 

 stone of quite different character, and some kind of rock is felt with a pole in the bed of the 

 stream. The limestone is dark argillaceous, and occasionally arenaceous. This is the pipe- 

 stone from which the Indians of this vicinity cut their pipes. It has somewhat the ap- 

 pearance of a hydraulic lirpestone. 



